MedClinic > Blog > Traumatology > Knee joint


The knee joint is the most complex joint in humans. For several reasons, the knee joint is injured more often than other joints. Many knee injuries can be treated conservatively, i.e. without surgery, and with other injuries, surgery has to be performed.

Do not delay a visit to a traumatologist, especially if:

  • During movements in the knee, joint painful clicks appeared
  • Knee became insecure, unstable, shin seems to slip out, or leg buckles
  • Pain does not go away
  • It is impossible to move the knee, or the movement is limited by something (something is interfering)
  • Lameness appeared
  • Knee swelling

Knee pain: symptoms, diagnosis and treatment

Pain in the knee joint is a fairly common phenomenon. Both elderly people and young people, athletes, young mothers can complain about it. Sometimes its causes and character may not be cause for concern. For example, if you hurt yourself, fell, and pain does not manifest itself too intensely, becomes less noticeable every day and after a short time passes completely, in such cases, it is not necessary to go to a clinic at all. But, if you are worried about acute pain even at rest, which does not go away and does not even subside long enough, intensifies after exercise and/or after running, you need to plan your visit to a doctor to protect your leg from the irreparable consequences of injuries to the knee joint.

Causes of knee pain

To determine the cause of pain, you first need to figure out in which part of the knee there is discomfort. Indeed, different diseases sometimes have very similar symptoms, and the key to successful treatment is the correct diagnosis. So, there may be pain in the knee from the inside, from the side, pain under the knee. And all this indicates different injuries.

Conditionally, causes of pain in the knee joint can be divided into four groups.


First group

It includes various systemic diseases, due to which there is a constant pain in the knee:

  • Infectious diseases of the knee joint (Reiter’s syndrome, tuberculosis, Lyme disease);
  • Fibromyalgia;
  • Charcot Arthropathy;
  • Paget’s disease;
  • A variety of arthritis (systemic lupus erythematosus, polymyalgia rheumatic, rheumatoid arthritis, inflammatory bowel arthritis, gout).

Second group

This includes both individual features of the structure of the knee joint, and its diseases, in which there may be quite severe pain in the knees:

  • Medial patellar plica syndrome;
  • Patellar ligament tendonitis;
  • Habitual dislocation or, as it is also called, chronic instability of patella;
  • Arthrosis of the knee joint and its varieties;
  • Popliteus tendinopathy
  • Biceps femoris tendinopathy
  • Bursitis in the area of ​​the knee joint;
  • Dysplasia of the condyles of femur;
  • Subluxations and inclinations of patella;
  • Osteochondritis dissecans;
  • Baker Cyst;
  • Osgood-Schlatter disease and more.


Third group

It includes a kind of indirect signs, which are the main reason that provokes pain in the knee. But sometimes they are quite difficult to diagnose. The most common causes are:

  • Injuries and various diseases of the hip apparatus;
  • Neurological diseases of the spine.


Fourth group

There we include knee injuries, due to which the joint suffered various injuries. Because of them, a fairly sharp knee pain can occur, as well as undefined, episodic, but long-lasting during flexion and extension:

  • Knee injuries of varying intensity;
  • Tears: posterior and anterior cruciate ligaments, meniscus, patellar ligament, quadriceps femoris muscle-tendon, peroneal and tibial collateral ligaments;
  • Instability and rupture of the upper tibiofibular articulation;
  • Fractures: osteochondral, patellar (kneecap), of the condyles of the femur, of distal femur, upper tibia;
  • Separation of tibial tuberosity.

Besides to such a conditional separation, pain also happens for other reasons that are very difficult to identify and classify. These include, for example, osteomyelitis, cancer, toxic synovitis.

Also, if you take a close look, you can identify that many of the reasons that apply to different groups are interrelated. For example, arthrosis may occur due to a meniscus rupture. Therefore, for identifying the exact reason for knee pain, a comprehensive examination is often necessary, especially if there is no direct joint injury.


What to do if your knee hurts

First and foremost – no self-medication! With this, you are only very likely to hurt a sore leg and aggravate the situation. Treatment should be prescribed only by a qualified specialist. All you can do at first is to limit physical activity, not to drink alcohol, not to take hot baths or showers.

If the pain is too strong, you can take an anaesthetic or apply ice, significantly limit the movement of the leg, or completely immobilise it.

It is highly recommended not to apply thermal compresses, put elastic bandages on the leg, as this can provoke oedema and increased pain.

If there is pain in children, do not hesitate at all – the faster you take the child to the doctor, the lower the risk of complications.


When you should not postpone a visit to a doctor

  • Strong swelling of the knee, which is visible, without even closely looking at it;
  • The movements are too limited or completely impossible: you get the feeling that something is stopping you bending or unbending your leg;
  • You began to limp;
  • The pain intensifies noticeably when running and even when walking, the foot seems to give way, it seems unstable;
  • When you move your knee, you feel or hear clicks that are accompanied by pain;
  • The pain, no matter how intense it is, does not go away for more than one week.

What treatment can a doctor prescribe?

Conservative treatment

It should be noted that after an injury, you should not try to fully stand on your foot, as well as move around without the help of others. Your task before visiting the hospital is to protect the knee from further, even greater damage.

If you went to the clinic immediately after injuring your knee, then at first all actions will be aimed at maximally removing the effects of trauma and uncomfortable sensations. So, the doctor will prescribe medications and procedures for relieving oedema, if any, and, of course, to minimise pain. It can be anti-inflammatory drugs, ice packs and, of course, rest for the leg. If hemarthrosis is diagnosed, it will be necessary to periodically pump out fluid that accumulates in the joint.

A little later, after carrying out the priority procedures, the doctor will try to return the joint mobility to you for normal life. How to treat knee pain without surgery? Exercises, as well as physiotherapy, can be prescribed. Exercising is necessary to prevent muscle atrophy, as well as return the composition to its former mobility. Also, special exercises will help strengthen quadriceps femoris and popliteal muscles.

They, in turn, ensure the stability of the knee, because, in the absence of it, development of early joint arthritis may occur.

Surgical treatment

Doctor can resort to it in the case when conservative methods did not bring the desired result and the stability of the joint is not at the proper level, thereby limiting a person in physical activity. In the vast majority of cases, the patient is prescribed arthroscopic surgery, during which it is possible to eliminate the most diverse causes of pain and discomfort.

It should be noted that even if it is obvious to the doctor who examined the knee immediately after the injury a course of physiotherapy, as well as exercises are still appointed. This is done to relieve oedema and restore joint mobility.

The knee joint is a very important part of our body, which provides full movement and, as a result, the functioning of a person. Therefore, if you are concerned about pain and other unpleasant sensations in the knee area, it is better not to hesitate and consult a doctor to protect yourself from the terrible consequences of untimely medical care and surgical intervention.


Menisci of the knee are cartilage pads. Menisci perform different functions: distribute the load, absorb shock, reduce contact load, act as stabilizers, limit the amplitude of movements, participate in proprioceptive afferentation during movements in the knee joint, i.e. signal our brain about the position of the knee joint. The first four are considered to be the main among these functions – load distribution, shock absorption, distribution of contact load and stabilisation. During movements in the knee joint, menisci contract, their shape changes.

Structure of Menisci

There are two menisci in the knee joint – external (lateral) and internal (medial). In front of the joint, they are connected by a transverse ligament.

The external meniscus is more mobile than the internal, therefore its traumatic injuries occur less frequently.

The internal meniscus is less mobile and is associated with the internal lateral ligament of the knee joint, so trauma is often combined with damage to this ligament.

On the side of the joint, menisci are fused to the capsule of the joint and receive blood supply from capsule arteries. Internal parts are deep in the joint and do not have their blood supply, and their tissues are nourished through the circulation of intraarticular fluid. Therefore, damage to the menisci near the joint capsule fuses well, and tears of the inner part, deep in the knee joint, do not fuse at all.

Meniscus injuries are the most common knee problem. In principle, meniscus tears can be traumatic, which more often occur as a result of trauma in young people and degenerative, which are more likely to occur in older people and can occur without trauma against the background of degenerative changes in the meniscus, as a variant of course of arthrosis of the knee joint. A doctor can diagnose meniscus rupture. To confirm the diagnosis of meniscus rupture, magnetic resonance imaging (MRI) may be required. Less commonly, an ultrasound scan can be used to confirm the diagnosis.

Most often, surgical treatment is used to treat meniscus diseases. Currently, the “gold standard” for meniscus damage is arthroscopy (examination of the joint cavity using a special optical system), during which, if possible, stitching of the damaged meniscus is performed. If stitching is not possible, as well as when the damage is localized in the extravascular part, a partial or complete removal of the meniscus is performed.

Cruciate ligaments

The cruciate ligaments are located in the cavity of the knee joint, they provide stability to the bones relative to each other. The most important ligaments of the knee joint include:

  • Cruciate ligaments that keep the lower leg from being displaced anteriorly (anterior cruciate ligament) and posteriorly (posterior cruciate ligament).
  • The tibial collateral ligament (medial collateral ligament), which keeps lower leg from deflecting outward.
  • Fibular collateral ligament (external lateral ligament), which keeps the lower leg from deflecting inside.

Damage and rupture of the anterior cruciate ligament are a very common injury.

Anterior Cruciate Ligament

The anterior cruciate ligament (ACL) is one of the most injured ligaments of the knee joint, located in the very center of the knee joint. The anterior cruciate ligament starts from the inner surface of lateral condyle of femur, passing through the intercondylar fossa goes down, forward and inward, attaching to the anterior intercondylar area of the tibia. The anterior cruciate ligament stabilises the knee joint and prevents the tibia from moving excessively forward, and also holds the outer condyle of the tibia.

In addition to the fact that the anterior cruciate ligament of the knee joint performs a stabilisation function (keeps the tibia from moving forward and inward), it also has nerve endings that indicate in which position (bent or unbent) the knee joint is located.

The anterior cruciate ligament has virtually no blood vessels.

Perpendicular to the anterior cruciate ligament, posterior cruciate ligament is located beside it, and if you look at these ligaments from the front, you can see how they form a cross, which gave these ligaments their name – cruciate ligaments. The average length of the anterior cruciate ligament is 3 centimetres, and the width is 7-12 mm.

Posterior cruciate ligament

The posterior cruciate ligament (PCL) is located perpendicular to the anterior cruciate ligament, forming a cruciform structure in the very center of the joint. It stabilises the knee joint and keeps lower leg from shifting back.

Meniscus injury

Menisci are cartilaginous layers inside the knee joint, which mainly perform shock-absorbing and stabilizing functions. There are two menisci of the knee joint: internal (medial) and external (lateral).

Causes of meniscus tear

Among the internal injuries of the knee joint, meniscus injuries take first place. The cause of meniscus tear is an indirect or combined injury, accompanied by rotation of the lower leg: externally, as characteristic of the medial meniscus, and internally is characteristic of the external meniscus.

A doctor can diagnose meniscus rupture. To confirm the diagnosis of meniscus rupture, magnetic resonance imaging (MRI) may be required.

Also, meniscus damage is possible with a sharp excessive extension of the joint from a bent position, abduction and reduction of the lower leg. Less commonly, it can happen when exposed to direct trauma in cases of the joint being blown against the edge of a step or by any moving object.

Repeated direct trauma or bruising can lead to chronic trauma of the menisci (meniscopathy) and further to its rupture. Degenerative changes in the meniscus can develop as a result of chronic microtraumas, after rheumatism, gout, chronic intoxication. Especially these changes can occur in people who have to walk a lot of work while standing. With the combined mechanism of injury, in addition to menisci, capsule, ligamentous apparatus, adipose body, cartilage and other internal components of the joint are usually damaged.

Types of meniscus tears

  • separation of the meniscus from attachment points in the region of posterior and anterior horns and meniscus body in the pericapsular zone;
  • ruptures of posterior and anterior horns and meniscus body in the transchondral zone;
  • various combinations of the listed damage;
  • excessive mobility of menisci (rupture of intermeniscal ligaments, meniscus degeneration);
  • chronic trauma and meniscus degeneration, cystic degeneration of menisci (mainly external).

Meniscus tears can be complete, incomplete, longitudinal (“vertical tear”), transverse, flap-like, fragmented.

Symptoms of a meniscus tear

At a young age, meniscus tears occur more often as a result of trauma. As a rule, rupture occurs during torsion on one leg, i.e. with axial load in combination with rotation of the lower leg. For example, such an injury can occur when running, when one leg suddenly rises on an uneven surface, when landing on one leg with torsion of the body. However, meniscus tear can occur with another mechanism of injury.

Usually, immediately after tear, pain in the knee appears the joint swells. If meniscus rupture affects the red zone, i.e. the place where there are blood vessels in the meniscus, hemarthrosis occurs – accumulation of blood in the joint. It is manifested by bulging, swelling above the patella (kneecap).

When a meniscus ruptures, the detached and dangling part of meniscus begins to interfere with movements in the knee joint. Small tears can cause painful clicks or a feeling of obstructed movement. With large ruptures, blocking of the joint is possible because a relatively large size of the torn and dangling meniscus fragment moves to the center of the joint and makes some movements impossible, i.e. the joint “wedges”. With ruptures of the horn of meniscus, flexion is more often limited, with ruptures of the body of meniscus and its front horn, extension in the knee joint suffers.

Pain when tearing a meniscus can be so strong that it is impossible to step on the foot, and sometimes the tear of meniscus manifests itself only as pain with certain movements, for example, when walking down from the stairs. At the same time, climbing stairs can be completely painless.

It is worth noting that blockade of the knee joint can be caused not only by rupture of a meniscus but also by other reasons, for example, rupture of the anterior cruciate ligament, free intraarticular body, including a laced fragment of cartilage in Koenig’s disease, medial patellar plica syndrome, osteochondral fractures of the condyles of tibia and many other causes.

In acute tear, combined with damage to the anterior cruciate ligament, swelling can develop faster and be more pronounced. Damage to the anterior cruciate ligament is often accompanied by a tear of the lateral meniscus. This is because when a ligament is torn, the outer part of the tibia is dislocated forward and the lateral meniscus is infringed between femur and tibia.

Chronic, or degenerative, tears often occur in people older than 40 years; pain and swelling, in this case, develop gradually, and it is not always possible to detect a sharp increase in them. Often it is impossible to detect a history of falling or only a very minor effect is detected, such as bending legs, squats, or tearing may appear even simply when getting up from a chair. At the same time, blockage of the joint may also occur, however, degenerative breaks often manifest only in pain. It is worth noting that with degenerative rupture of a meniscus, the neighbouring cartilage that covers femur or more often tibia is often damaged.

Like acute meniscus tears, degenerative tears can manifest in a varying severity of symptoms. Sometimes it is completely impossible to step on the foot because of pain or even slightly move it, and sometimes pain appears only when descending the stairs, doing squats.

Meniscus injury diagnosis

The main sign of meniscus tear is pain in the knee joint, which occurs or intensifies with a certain movement. The severity of pain depends on the place where meniscus tore (body, posterior horn, anterior horn), the size of the gap, the time that has passed since the injury.

The diagnosis of a meniscus tear cannot be made independently – you need to contact an orthopaedic surgeon. You should contact a specialist who is directly involved in treating patients with injuries and diseases of the knee joint.

On the photo: MRI of a normal and damaged meniscus

Meniscus tear – treatment

The treatment of meniscus injuries depends on the severity of the condition. At one extreme there is a small gap or degenerative meniscus changes that should initially be treated conservatively. On the opposite extreme, there are a lot of painful “vertical” type teas, which cause blockage of the knee joint and require direct arthroscopic surgery. Most real meniscus injuries are somewhere between these two extreme conditions and, accordingly, so is the decision regarding the treatment. Therefore, a decision on immediate surgery should be made based on the severity of symptoms and signs, taking into account the sportsman’s level and workload.

Surgical treatment

Currently, the gold standard” for treating meniscus tearing of the knee joint is arthroscopy, a low-traumatic operation performed through two incisions, each one centimetre long. Other techniques (meniscus suturing, meniscus transplantation) are also used, but they give less reliable results.

During arthroscopy, the dangling and torn part of meniscus is removed and the inner edge of the meniscus is levelled with special surgical instruments. Note that only a part of the meniscus is removed, and not the entire meniscus. The torn part of meniscus no longer fulfils its function, so there is no particular sense in preserving it.

After arthroscopic surgery, you can walk on the same day, but for a full recovery, it may take from several days to several weeks.

Cruciate ligament tear

The anterior cruciate ligament (ACL) is one of the most injured ligaments of the knee joint. Among all other ligaments of the knee, the anterior cruciate is most often injured. For example, its tears occur 15-30 times more often than in the posterior. The mechanism of ACL injury is most often associated with sports and often consists of valgus deformity and pronation.

To determine the tear of the anterior cruciate ligament, the doctor performs diagnostics, the most indicative of which is MRI.

Causes of the cruciate ligament tear

Based on the function performed by the ACL (keeping lower leg from moving forward and inward), the trauma mechanism, in which the anterior cruciate ligament is stretched or damaged, becomes clear. As a rule, the torsion on the supporting leg happens, when the body with the thigh rotates outward, and the tibia with the foot remains in place.

However, the mechanism and causes of rupture of the anterior cruciate ligament are more complex. Fundamentally, the causes can be identified as direct injury (contact mechanism: impact on the lower leg, thigh) and indirect (non-contact mechanism: torsion on the leg during sharp braking, landing after a jump, etc.).

Deviation of tibia outwards and torsion of thigh inwards. This mechanism of rupture of the anterior cruciate ligament is the most common. Often it occurs in handball, basketball, soccer and volleyball when you need to sharply turn around when running or when landing after a jump with the body turned inwards from the supporting leg. With this mechanism of injury, a rupture of the inner meniscus can occur. If this movement is very strong, then three structures can be damaged: the anterior cruciate ligament, the inner meniscus and the inner lateral ligament. This damage to the knee joint is also called the “unfortunate triad” or “knee joint explosion”.

The main symptom of the anterior cruciate ligament tear is joint instability. Prolonged neglect of instability leads to early arthritis of the knee joint. With severe instability, surgery is recommended consisting in reconstruction of the anterior cruciate ligament, which can be carried out in several ways. 6 months after the tear of the ACL, a person can return to the previous level of physical activity.

Understanding the mechanism of damage to the ligament is of great importance for the diagnosis and prevention of this injury. Knowledge of the mechanism will tell a doctor the likelihood of ligament injury in each case. This is only possible with a clear detailed description of the moment of injury by the athlete himself. That is why this knowledge is necessary not only for doctors but also for athletes. Understanding the mechanism of injury will help athletes avoid situations leading to tear.

The non-contact mechanism of injury predominates among injuries of the anterior cruciate ligament. This mechanism assumes that the injured joint is not exposed to external stress. Otherwise, this mechanism is called contact, the most common of which is a direct blow to the joint, as well as on the lower leg or thigh.

Symptoms of Cruciate Ligament Damage

Damage to the anterior cruciate ligament is usually preceded by an injury to the knee joint, immediately after which there is pain and severe swelling of the knee. When the anterior cruciate ligament is torn, crackling is often heard, but this is a nonspecific symptom that occurs with ruptures of other ligaments of the knee joint. Also, at the time of injury, the sensation of “dislocation” of tibia anterior or to the side is possible. In such cases, you need to see a doctor.

First of all, a traumatologist will find out the mechanism of injury, which will help to suspect not only damage to the anterior cruciate ligament but also other structures (for example, the posterior cruciate ligament, the external and internal lateral collateral ligaments).

When the anterior cruciate ligament tears, blood enters the joint cavity – this condition is called hemarthrosis. In the first few days after the injury, this hemarthrosis and pain can be so pronounced that a full examination of the joint using the doctor’s hands is impossible, and it is only thanks to the examination by the doctor’s hands that the diagnosis of rupture of the anterior cruciate ligament can be made.

Diagnosis of injured ligaments

After a doctor carefully familiarises himself with the mechanism of injury, he will begin to test your knee joints. A healthy knee is examined first to familiarise a patient with the technique of examination, as well as to have the opportunity to compare the test results between the healthy and the injured leg. With a thorough examination, tear of the anterior cruciate ligament can be diagnosed without additional research methods. But, since it is necessary to exclude other injuries (fractures of the tibial condyles and femoral condyles, patellar fractures, Segond fractures, torn menisci, lateral ligaments, etc.), the doctor also uses other instrumental examination methods (radiography, magnetic resonance imaging, ultrasound).

The posterior cruciate ligament (PCL) is located immediately behind the ACL. To tear the posterior cruciate ligament, you need a very strong impact. The most common rupture mechanism is a frontal lower leg blow, which happens in road accidents and sports. For example, it can be a bumper injury – when the bumper of a low car hits the upper part of the lower leg, but below the knee. Drivers may have a similar mechanism of injury – during a stagnation, the driver by inertia moves forward and hits the dashboard of the car with his knee. To prevent such damage, modern cars have airbags under the steering wheel. The only way to prevent it, in addition to limiting activity, is to strengthen the muscles of the knee joint.

If there is a suspicion of an injury to the posterior cruciate ligament, it is very important to examine the ligaments of the posterior external section of the knee joint (posterolateral angle), since in 60% of cases they also turn out to be damaged.

To confirm the diagnosis of tear of the posterior cruciate ligament and find out whether there are other injuries it is needed to use instrumental examination methods, the main of which are radiography and magnetic resonance imaging. Ultrasound examination for cruciate ligament injuries is not informative.

Given that the posterior cruciate ligament tears appear due to very severe injuries, X-rays of the knee joint are primarily performed on which fractures of the condyles of the femur, condyles of the tibia, and the patella can be detected. Damage to the posterior cruciate ligament may be indicated by a slight subluxation of the lower leg, visible on the radiograph in the lateral view. It is possible to increase the informative content of X-rays easily: during the picturing, the test of «rear drawer» is performed, and the picture is compared with the same picture of a healthy knee.

Treatment for the tear

Conservative treatment of injuries of the anterior cruciate ligament usually does not give good results in people returning to intensive sports. Pain, swelling and instability periodically occur in 56–89% of athletes with anterior cruciate ligament tears after conservative treatment.

Currently, the gold standard” for treatment of tears of the knee ligaments is arthroscopy, a minimally traumatic operation that is performed through two incisions, each one centimetre long.

It is impossible to stitch the ruptured anterior cruciate ligament – grafts are used to repair it, i.e. other tendons (an autograft from the patellar ligament, an autograft from the hamstrings, allografts) or synthetic prostheses.

Autoplasty of the anterior cruciate ligament

Arthroscopy is done if after conservative treatment the stability of the joint does not meet the requirements of physical activity. It is worth noting that the operation gives the best results against the background of good movements in the knee joint and strong muscles, which once again emphasises the importance of the conservative stage of treatment. On average, operations to restore the anterior cruciate ligament in non-athletes are done 6 months after the rupture, but this does not mean that later the operation does not need to be done. It happens sometimes that it is done 5-7 years after the injury. In principle, the operation can be performed at any time after the injury, except in cases when a pronounced arthrosis develops in the knee joint against the background of the anterior cruciate ligament tear and subsequent instability of the knee joint.

The purpose of plastic surgery is to restore the anterior cruciate ligament to return a patient to the desired level of physical activity as soon as possible and to avoid complications, which primarily include arthrosis. Improvement of surgical technique and rehabilitation methods has led to the fact that more than 90% of patients continue to play sports and are completely satisfied with the treatment results. The average rehabilitation period is 4-6 months, but some professional athletes successfully begin to compete even after 3 months. The criteria for admission to sports activities may vary, but they are always oriented to one degree or another on the results of functional tests, patient’s sensations, and examination data. The most generally accepted criteria are as follows: restoration of the amplitude of movements, increase in shin mobility according to goniometry no more than 2-3 mm in comparison with a healthy leg, quadriceps muscle strength is at least 85% of normal, restoration of the strength of the posterior thigh muscle group, all functional indicators are at least 85% of normal.




Коленный сустав

Коленный сустав – самый сложный сустав человека. Ввиду целого ряда причин он травмируется чаще, чем другие суставы.